Hi,
Using CONFIG_EXTRA_ENV_SETTINGS should be good enough to provide the fallback defaults. However, the users can still mess the things up, but again, they can do that already in many places.
I disagree. In my case that is a last resort recovery. And it should work in any case. Even if the user has messed up anything (except from erasing the bootloader in the SPI flash ;)).
In summary, the registered (compiled-in) command should always take precedence. If one wants to supply a default command which can be changed later, that can go via the (compiled-in) default environment.
Sorry, this is a bit confusing to me. Didn't you write above that the users should be able to change the associated commands through the environment variables?
I had two kinds of button commands in mind: immutable ones and mutable ones. The first can be achieved with compiled-in commands, the second with a default environment and environment variables.
Also, whether a command is a mutable one or not is the decision of the developer (or the one who's compiling/configuring u-boot), not the user.
-michael